1. Field of the Invention
The present invention relates in general to press fitting tools that press fit a given element or part to an opening formed in a work, more particularly to the press fitting tools of a type that press fits the given element to the opening by practically using a flexibility possessed by the element. More specifically, the present invention relates to a press fitting tool that is suitable for press fitting a spring pin of generally C-shaped cross section to aligned holes of two works to tightly unite the same.
2. Description of the Related Art
Hitherto, various press fitting tools have been proposed and put into a practical use particularly in the automotive parts assembling field.
One of such tools is described in Japanese Laid-open Patent Application (Tokkaihei) 8-71861. The tool of this publication is used for assembling an automotive power transmission and constructed to press fit a spring pin to aligned pin holes, one being a pin hole formed in a shift rod (first work) and the other being a pin hole formed in a boss portion of a shift fork (second work). In operation, the spring pin is fed from a spring pin feeder to a spring pin holder that holds the spring pin, and then, the spring pin holder is turned about its axis to place and position the spring pin accurately on an axis of the aligned pin holes. Then, a press rod is strongly pressed against the spring pin to thrust the same into the aligned pin holes.
In the above-mentioned known tool, the spring pin used is of a type having a generally C-shaped cross section. That is, fitting of the spring pin in the aligned pin holes is effected by a radially expanding return force produced when the same is resiliently compressed in a radially inward direction. In other words, in a free condition wherein no external force is applied to the spring pin, the same has an outer diameter that is larger than a diameter of the aligned pin holes. For processing the press fitting of the spring pin, a leading end of the spring pin is brought into contact with a peripheral edge of an inlet portion of the aligned pin holes and then, with the pressing work of the press rod, pressed into the aligned pin holes while being reduced in diameter.